What is the interest rate called that banks charge each other for overnight loans of $1 million or more?

The interest rate that banks charge each other for overnight loans of $1 million or more is referred to as the federal funds rate. This rate plays a crucial role in the overall economy as it is a benchmark for other interest rates, influencing lending and borrowing costs throughout the financial system.

When banks have surplus reserves, they may lend those excess funds to other banks that have short-term deficits. The transactions occur at the federal funds rate, which helps regulate the amount of money that banks have available for lending and affects liquidity in the market. The federal funds rate is closely monitored by the Federal Reserve, as changes to it can influence inflation, employment, and economic growth.

In contrast, the spread rate typically refers to the difference between interest rates on loans and deposits, the discount rate is the interest rate charged to commercial banks for short-term loans from the Federal Reserve, and the prime rate is the interest rate that commercial banks charge their most credit-worthy customers. While these rates are all related to the banking system and influence borrowing costs, they do not specifically apply to the overnight lending between banks, which is why the federal funds rate is the correct answer.